udf: improve readability of do_udf_readdir

index 174d2fc..c26e281 100644
@@ -57,6 +57,7 @@ static int do_udf_readdir(struct inode *dir, struct file *filp,
 	int i, num;
 	unsigned int dt_type;
 	struct extent_position epos = { NULL, 0, {0, 0} };
+	unsigned char bits;
 
 	if (nf_pos >= size)
 		return 0;

@@ -65,12 +66,14 @@ static int do_udf_readdir(struct inode *dir, struct file *filp,
 		nf_pos = (udf_ext0_offset(dir) >> 2);
 
 	fibh.soffset = fibh.eoffset = (nf_pos & ((dir->i_sb->s_blocksize - 1) >> 2)) << 2;
+	bits = dir->i_sb->s_blocksize_bits;
+
 	if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_IN_ICB) {
 		fibh.sbh = fibh.ebh = NULL;
-	} else if (inode_bmap(dir, nf_pos >> (dir->i_sb->s_blocksize_bits - 2),
+	} else if (inode_bmap(dir, nf_pos >> (bits - 2),
 			      &epos, &eloc, &elen, &offset) == (EXT_RECORDED_ALLOCATED >> 30)) {
 		block = udf_get_lb_pblock(dir->i_sb, eloc, offset);
-		if ((++offset << dir->i_sb->s_blocksize_bits) < elen) {
+		if ((++offset << bits) < elen) {
 			if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_SHORT)
 				epos.offset -= sizeof(short_ad);
 			else if (UDF_I_ALLOCTYPE(dir) == ICBTAG_FLAG_AD_LONG)

@@ -84,10 +87,10 @@ static int do_udf_readdir(struct inode *dir, struct file *filp,
 			return -EIO;
 		}
 
-		if (!(offset & ((16 >> (dir->i_sb->s_blocksize_bits - 9)) - 1))) {
-			i = 16 >> (dir->i_sb->s_blocksize_bits - 9);
-			if (i + offset > (elen >> dir->i_sb->s_blocksize_bits))
-				i = (elen >> dir->i_sb->s_blocksize_bits) - offset;
+		if (!(offset & ((16 >> (bits - 9)) - 1))) {
+			i = 16 >> (bits - 9);
+			if (i + offset > (elen >> bits))
+				i = (elen >> bits) - offset;
 			for (num = 0; i > 0; i--) {
 				block = udf_get_lb_pblock(dir->i_sb, eloc, offset + i);
 				tmp = udf_tgetblk(dir->i_sb, block);